A virtualization system can provide a plurality of environments called virtual machines on a physical machine. The virtual machines operate in a virtual region managed by a virtualization program such as a hypervisor, for example.
A power supply of a server that implements the virtualization system is connected to an uninterruptible power supply (UPS) device provided for a power outage. At a time of a power outage, the server is supplied with power from a battery of the UPS and shuts down the virtualization system.
The following describes shutdown processing operation in a virtualization system according to a related technique with reference to FIG. 17. FIG. 17 is a schematic diagram illustrating the shutdown processing operation in a virtualization system according to a related technique. When a power outage occurs as illustrated in FIG. 17, a UPS detects the power outage (step S901) and supplies power from a battery (step S902).
A server waits for a certain period of time and then determines whether the server performs the processing to shut down the virtualization system (step S903). After the certain period of waiting time elapses, the server starts the shutdown processing of the virtualization system (step S904). In the shutdown processing, the server ends guest operating systems (OSs) and applications, and thereafter ends a virtualization program. The processing typically takes a few minutes. The UPS continues to supply power during the processing time, and thereafter turns off the output (step S905).
When power is restored from the power outage, the UPS turns on the output (step S906). The server then activates a basic input/output system (BIOS) (step S907) and re-activates the virtualization system (step S908).
In this manner, the server automatically stores the states of the virtual machines and stops the processing of the virtual machines by shutting down the virtualization system. The server restores the stored states of the virtual machines and automatically activates the virtual machines by re-activating the virtualization system.
The following techniques are known as those provided for a power outage. For example, Japanese Laid-open Patent Publication No. 10-124405 discloses a technique in which part of information stored in a volatile memory is transferred to another apparatus when a power outage occurs in the main power supply of a point-of-sale (POS) system. For another example, Japanese Laid-open Patent Publication No. 2003-345528 discloses a technique in which configuration information stored in a volatile memory is saved in a disk using a UPS when an abnormal condition occurs in the main power supply of a disk array apparatus, and the information is used for restoration.
The related techniques described above, however, have a problem in that the number of UPSs is unable to be reduced.
Specifically, the shutdown processing of the virtualization system takes a few minutes and power needed during the processing is supplied from the UPS. The UPS needs to be provided for each server. Thus, a number of UPSs need to be provided for a plurality of servers. As a result, the number of UPSs increases in accordance with the number of servers. The disclosed techniques described above are not capable of reducing the number of UPSs.